As an army of pants strutted down the fall runways, it was clear that skirts and dresses are no longer a fancy-party necessity. Dressed up with a silk-muslin blouse ($1,890) and Trib Two suede calf boots ($1,240), these silk-and-cashmere-charmeuse embroidered pants ($8,270) look as if they’d leave a trail of glitter behind them (Yves Saint Laurent, 3 E. 57th St., nr. Fifth Ave.; 212-980-2970). In fact, many a designer turned out pairs worthy of a Studio 54 flashback. Expect to see lots of legs shimmering in various shades of metallic: black, gold, and bronze. For more of fall’s sparklers, click ahead.